Thanks for publishing this here. After some forth-and-back with my tester on iPad-Pro (M-series), I can confirm that dext driver load/testing is possible using TestFlight on iPad. For the iOS App, you only need : <plist version="1.0"> <dict> <key>com.apple.developer.driverkit.communicates-with-drivers</key> <true/> </dict> </plist> and nothing else (the usb entitlement shown above is not correct or needed for the iOS app). If the driver does not load, manually download the provisioning profile from developer and check entitlements. I use automatic signing by the way. Then Archive to app-store, and export to ipa on Desktop: again check what's included. In my case, I had all entitlements granted, and config correctly but UserClient would give an entitlement error on loading, beause on the iOS App target I had not selected the capability in Xcode(macOS target had lots of testing). Having only entitlement does not work with automtaic signing; even if entitlement is exported to app store correctly. using Xcode 26.3

I wanted to do this for my driver, that when multiple devices are plugged, the second USB driver instance changes its behaviour. Consider, that each driver runs in its own (kernel) process, talking to the app via its own (kernel) UserClient. The answer is right there = its not possible, because the address space is isolated as each driver runs in a sperate process (observe with ps). The only way I found, is to do this Driver1->UserClient1->App->UserClient2->Driver2. The app watches the plug/unplug in any case, and I created a special call that on the Device#2 plug = calls into driver2 and activates the feature. my 10 cents... PS: if this is a use-case then the app should handle this case (multiple devices plugged) anyways.

This is with: macOS 26.4.1, Xcode 26.3, MacStudio-M1 There is the message after the crash/reboot "Your computer restarted because of a problem" - but the stack trace is beingn - not my driver, nor the kernel/dextloder, there is no log in Console, no crash report in Console.